Color photography with azosubstituted couplers



Patented Jan. 13, 1945 COLOR PHOTOGRAPHY WITH AZO- SUBSTITUTED COUPLERSEdwin E. Jelley and Paul W. Vittum, Rochester, N. Y., assignors toEastman Kodak Company, Rochester, N .Y., a corporation of New Jersey NoDrawing. Application May 3, 1944, Serial No. 533,933

3 Claims. (Cl. 95-6) This invention relates to color photography andparticularly to a method for producing stable dye images in photographiclayers.

In Glass, Vittum, and Weissberger, U. S. patent applications Serial Nos.533,930, 533,931 and 533,932, filed May 3, 1944, there are describedcolored couplers having an azo-substituted reactive methylene group orreactive ethanol group. It has been found that these couplers react withthe development product of primary aromatic amino developing agents toform colored photographic images just as the couplers containingunsubstituted reactive methylene or ethanol groups react. The azo groupis removed during coupling and an azomethine or indophenol dye isproduced.

We have found that these colored couplers containing an azo-substitutedreactive methylene or reactive ethanol group may be incorporated in thephotographic emulsion layer and may be used to form the final dye image.According to the process, the emulsion layer contains a coupler havingthe color desired for the final dye image. After exposure of the layer,it is developed with a coupling developing agent, such asdiethyl-p-phenylenediamine during which step the coupler color isdestroyed at the points where development occurs leaving at these pointsan azomethine or indoaniline or indophenol dye image in place of thecolored coupler originally present. At the places where no developmentoccurs, the colored coupler is left intact. The layer is then subjectedto a suitable treatment, such as a strong acid bath which destroys andremoves the coupled dye without aiTecting the original colored coupler.The residual silver and silver halide are then removed, leaving areversed dye image composed of the originally incorporated coloredcoupler.

The following colored couplers are suitable for incorporation inphotographic layers according to our invention as well as the couplersdescribed in Glass, Vittum and Weissberger U. S. patent applicationsSerial Nos. 533,930, 533,931 and 533,952 referred to above.

(3) $03K OCH; OCH: S0311 $0311 I SO3H It will be seen that the color ofthe dye formed during color development is of no importance since thisdye is removed. The color of the original coupler is chosen to fulfillthe requirements for the final dye image.

The colored coupler is incorporated in the silver halide emulsion layerwhich is generally of the gelatino-silver bromide type, by forming thesodium salt of the coupler and dissolving the solution directly in theemulsion prior to coating or by incorporating the coupler in a solutionof a water-insoluble, water-permeable solvent as described in Mannes andGodowsky U. S. Patent 2,304,940 or our prior Patent 2,322,027. Theamounts of coupler employed will generally vary between 1.0 gram and 10grams per liter of wet emulsion. Thelayer containing the coupler isexposed in the usual way and is then developed in any of the usual colordevelopers, such as pphenylenediamine or p-aminophenol. A typicaldeveloper formula is as follows:

p-Aminodimethylam'line HCl grams 3 Sodium sulfite do 2 Potassium bromidedo 2 Sodium carbon do 20 Water to l ers 1 Hydrochloric acid concentratedcc 50 Water c-.. Isopropyl alcohol cc 850 The layer is then treated withsolutions of ferricyanide and hypo in the usual way to removeundeveloped silver and residual silver halide. The fragments of thecoupled dye destroyed by the acid treatment are also removed either bythis treatment or by the preceding acid treatment.

The removal of the silver and residual silver halide may be carried outprior to the acid treatment, or the acid treatment and the fixing may becarried out simultaneously.

Our process can be adapted to single layer or multi-layer materials. Inthe latter case the ma: terial may be arranged in the known manner togive natural-color reversal pictures. For example, the red-sensitivelayer containing cyan-col;- ored coupler would be coated on the supportfollowed by the green-sensitive layer containing magenta-colored couplerand the blue-sensitive layer containing yellow-colored coupler. In thismaterial, it would be advantageous to have sensitivity maXima which donot correspond with the absorption maxima of the colored couplers. Ourprocess may also be adapted to other known arrangements, such as, thoseleading to false color pictures.

It is advantageous in certain cases when using multi-layer materials toincorporate the colored coupler in only a single layer or in less thanall of the emulsion layers of the coating. The remaining emulsion layersmight contain colorless couplers incorporated directly in the emulsionlayer in the usual Way or incorporated in waterpermeable,water-insoluble solvents as described in the Marines and Godowsky U. S.Patent 2,304,949 and in our prior Patent 2,322,027 referred to above. Itmight also be advantageous to have one or more of the layers of themultilayer coating free of coupler so that the dye image could be formedin this layer by means of a coupler dissolved in the developingsolution.

Several advantages accrue from the use of a system having coloredcouplers in less than all of the layers of a multi-layer coating andcolorless couplers in the remaining emulsion layer. The layerscontaining the colored coupler would produce a positive image upondirect development in a color-forming developer, whereas. the layerscontaining the colorless couplers produced a negative image. cameramaterial is, therefore, a mixture of negative and positive components.However, by printing onto a similarly constituted paper or otherprinting material, a normal positive is obtained. A further advantage inthe case of multi-. layer materials coated in the normal order, that iswith the blue-sensitive layer outermost, is that the yellow filter layernormally coated between the top and middle emulsion layers can bedispensed with by use of a blue-sensitive emulsion layer containing ayellow-colored coupler. Furthermore, by using a magenta-colored couplerin the green-sensitive emulsion layer as well as a yellow-coloredcoupler in the blue-sensitive emulsion layer, red light, only wouldreach the bottom red-sensitive layer so that not only would no yellowfilter be, required but also the red-green color separation would beimproved.

A still further advantage in the use of both colored and uncoloredcouplers is the possibility of i proving the overall stability of thefinaldye images. 'In color processes in which eolorlesscow. plers areincorporated in the emulsion layers, it is not unusual to find that oneor? the final dye images is much less stable than the other two. Thepresent proposal would permit. the se of, a

The picture obtained on the colored coupler having higher stability thanthe unstable colorless coupler, so that the stability of the final dyeimages could be matched. This advantage is of course due to the higherstability of the azo dyes and is inherent in the colored couplers whichwe propose to use. Generally, the colored couplers containing azo groupsmay be selected to produce higher fastness to heat and light than can beobtained with the azomethine or indoaniline dyes normally obtained incolordevelopment processes.

In a specific embodiment of the use of a colored coupler in one of thelayers of a multi-layer coating and colorless couplers in the otherlayers,

'asupp ort of filrn or paper may be coated first with a red-sensitivesilver halide emulsion containing a dispersion of a coupler capable ofyield- .jing a cyan dye on development, followed by a clear interlayer,a green-sensitive silver halide emulsion containing a dispersion of a,coupler capable of yielding a magenta dye on development, another clearinterlayer, and then a, bluesensitive silver halide emulsion containinga dispersion of a yellow-colored coupler capablev of being destroyed ondevelopment to yield, an easily removable azomethine dye. Ananti-abrasion layer of clear gelatin may be coated as the final layer.

In this system, the red-sensitive emulsion layer may contain as the cyancoupler o-lauryl phenol incorporated directly in the emulsion or adispersion of (l) 2-0:-(4'-tert.amylphenoxy )-butyrylamino-l-phenol or(2) 5- (N- (v-phenylpropyl) N-(p-amylbenzoyl) amino) 1' naphthol, in n,-butyl phthalate or tri-orthocresylphosphate age cording to the method ofour prior Patent 2,322,027.

The green-sensitive emulsion layer may con,- tain a dispersion of (1)1-phenyl 3;n-pentadecy1 S-pyrazolone, (2) 1-phenyl-3:palrnitylamino-E:pyrazolone, or (3) l-cyanoacetyl-g-tert.amyldiphenyl. A dispersion inn-ainylphthalate, ethyl sebacate, or N-nr-amylphthalimide according toour prior Patent 2,322,027 of (1) 1-p-.(p,.- tertbutylphenoxy-phenyl)-3- m (p tertamyl-H phenoxybenzoylamino)-5-pyragolone, or (2) 2-cyanoacetylcournarone-5-sulfon- N ('y phenylw propyl)-p-tert.amylanilide may also be used. All ofthese couplers producemagenta d es.

The blue-Sensitive. mulsion. lay r a c ntai a dispersion of one of thefollowing yellow-colored couplers dispersed directly in the, emulsionlayer or used with a coupler solv nt as described in ourprior Patent2,322,027:

ing developer and then removing the azomethi-ne dye from the originallyblue-sensitive layer and also removing all of the silver and silverhalide is shown in the following diagram:

6 linked to said reactive group and to an aryl radical, exposing saidlayer and developing it with a primary aromatic amino developing agentwhich simultaneously destroys the azo linkage It is apparent from thischart, which represents the three emulsion layers and shows the color ofthe image produced by exposure to various colors and the colors obtainedby passing white light through the material as in printing, that thecolors obtained in the negative bear no direct relation to the colors ofthe original. This material would not give a positive copy by reversalprocessin but upon printing the negative onto a similar material thecolors of the original are reproduced.

For processing a material of this type a normal color developer isemployed, that is one containing as the developing agent a primaryaromatic washed, treated with an acid bath to remove the azomethine dyefrom the top emulsion layer, such as the acid loath listed above,treated with ierricyanide to convert the silver to silver ferrocyanide,and finally treated with hypo to remove the silver salts. 4

Since it is advantageous in some cases to confine the use of the aciddye bleach bath to the upper lay or layers, this bath may containloading agents to control its penetration. The steps involving the useof the acid bleach bath and the ferricyanide bath can be combined byusing a hydrochloric acidquinone bath, such as that described in column2, lines 17 to 22, of Mannes and Godowsky U. S. Patent 2,113,329.

With the colored couplers used according to our invention,insolubilizing groups may be present in the coupler molecule to renderthe couplers non-diifusing in the emulsion layer or layers in which theyare incorporated. These groups may be so chosen that the fragments ofthe coupler obtained after development and acid treatment will be smallenough to permit easy diffusion and removal from the film.

It will be understood that our invention is capable of numerousmodifications not herein 55 specifically mentioned and that ourinvention is to be taken as limited only by the scope of the appendedclaims.

We claim:

1. The method of producing a colored image in a photographic silverhalide layer, which comprises incorporating in said layer a coloredcoupler having an azo-substituted reactive group selected from the classconsisting of methylene and ethanol groups, the azo linkage beingdirectly and forms a dye image in the exposed regions by coupling of thedevelopment product of the developer with the residue of the coloredcoupler, treating said layer with an acid solution to destroy saidcoupled dye image Without affecting said colored coupler, and removingsilver and silver halide from said layer along with the destroyedcoupled dye image.

2. The method of producing a colored image in a photographic silverhalide layer which comprises incorporating in said layer a coloredcoupler having an azo-substituted reactive methylene group, the azolinkage being directly linked to said reactive group and to an arylradical, exposing said layer and developing it with a primary aromaticamino developing agent which simultaneously destroys the azo linkage andforms a dye image in the exposed regions by coupling of the developmentproduct of the developer with the residue of the colored coupler,treating said layer with an acid solution to destroy said coupled dyeimage without afiectin said colored coupler, and removing silver andsilver halide from said layer along with the destroyed coupled dyeimage.

3. The method of producing a colored image in a photographic silverhalide layer which comprises incorporating in said layer a coloredcoupler having an azo-substituted reactive ethanol group, the azolinkage being directly linked to said reactive group and to an arylradical, exposing said layer and developing it with a primary aromaticamino developing agent which simultaneously destroys the azo linkage andforms a dye image in the exposed regions by coupling of the developmentproduct of the developer with the residue of the colored coupler,treating said layer with an acid solution to destroy said coupled dyeimage without afiecting said colored coupler, and removing silver andsilver halide from said layer along with the destroyed coupled dyeimage.

EDWIN E. JELLEY. PAUL W. VITTUM.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,322,001 Ehrenfried June 15,1943 (Other references on following page) Number Woodward Feb. 22, 1944Name Date Schinzel Jan. '7, 1941 Schinzel Nov. 18, 1941 Peterson Jan.12, 1943 Woodward Oct. 6, 1942 FOREIGN PATENTS Country Date GreatBritain Apr. 11, 1939

